1. Field of the Invention
This invention relates to a combustor dome assembly for a gas turbine engine and, more particularly, to an apparatus and method for atomizing water passing out of a downstream end of a venturi in the combustor dome assembly in order to minimize the effects of water erosion on the various components of the combustor dome assembly.
2. Description of Related Art
In the design of gas turbine engines, it has become important to not only provide a combustor apparatus which is efficient, but one which minimizes undesirable emissions as well. One manner of diminishing emissions, such as CO and NO.sub.x, involves the injection of water into the combustor to reduce the temperature therein. Typically, the water is supplied through a nozzle circuit in a fuel nozzle which also provides natural gas to the combustor. A swirler coupled to a venturi provides a swirled airflow which causes the water and fuel to mix and swirl in a frusto-conical manner. Some of the water is swirled against an inner surface of the venturi thereby causing a film of water to travel towards a downstream end of the venturi. In combustor designs of the past, the swirling film of water would exit the downstream end of the venturi in relatively large droplets which would project radially outward due to the centrifugal force of the swirling water. It was not uncommon that the water droplets would impact or impinge, for example, the wall of a swirl cup, trumpet, dome plate, rivet band of a combustor dome assembly in the combustor. This water impingement caused thermal distress and erosion to the various components. The cause of thermal distress and erosion to the various components stems from relatively cold water impacting the relatively hot metal surfaces of the swirl cup, trumpet, dome plate, and rivet band.
Thus, while water injection has been effective in combatting emissions, such injection has had the undesirable effect of causing thermal distress and erosion to the swirl cup, trumpet, dome plate and rivet band of the combustor dome assembly.